The present invention relates to a cutting tool for turning operations. More specifically the invention relates to a cutting tool with an improved radial adjustment device for a bar peeling operation performed on solid or hollow bars formed of stainless steel or other heat resistant materials. The cutting tool comprises a holder equipped with one or several cutting inserts including an upper chip face, an opposite bottom face and a clearance face located therebetween, whereby the intersection of the chip face and the clearance face forms a cutting edge. Each insert is made of cemented carbide or similar wear resistant material.
Bar peeling as a metalworking operation means that an elongated bar is axially displaced through a central hole of a rotary cutter head. The cutter head is provided with several tools which remove from the bar a thin layer of millscale, surface cracks, etc., that results from the hot rolling of such slid or hollow bars. In order to achieve the best results regarding tolerances and surface finish, two different types of inserts, i.e., roughing and finishing inserts, are usually combined in the same holder.
After the mounting of the holder into its location in the rotary head cutter it is desirable to be able to make a fine adjustment of the exact radial position of each cutting insert (normally four inserts). This adjustment is usually accomplished by grinding the insert after it has been put into its location in the holder. The disadvantage of this method is that grinding the insert results in the removal of a surface layer that normally has been deposited on the surface of the insert, normally by CVD-technique, for the purpose of increasing the lifetime of the insert. Further, it is never possible to perform exactly the same amount of grinding on each of these four inserts which makes the tool less precise. According to an alternative method, precision is improved by arranging spacer plates in the toolholder for adjustment thereof. Such a procedure, however, is time-consuming and does not give precise results.
In EP-A-131 784 (the disclosure of which is incorporated by reference herein) there is disclosed a device for radial adjustment that is mounted into the holder which carries the cutting insert. This device comprises an adjustable wedge element one surface of which is in direct surface contact with a separate adjusting element. There is a large risk of vibrations with such tool, partly because the adjusting element is insufficiently dimensioned, and partly because the use of a single clamping screw is insufficient and is likely to cause a play in the tool which will lead to undesirable vibrations. (See also U.S. Pat. No. 4,261,235 which discloses a bar peeling tool having a plurality of insert holders mounted to a cutter head.)